Feed mechanism for sewing machines



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F. A. LARSON I FEED MECHANISM FOR SEWING MACHINES H Original Filed p 30 1920 Earl: (ZLaroon Patented Jan. 25, 1927. ,7

PATENT OFFICE.

IELRANK A. LARSON, OF LYNN, MASSACHUSETTS.

MECHANISM FOR SEWING MACHINES.

Substitute for application Serial No. 413,818, filed September'30, 1920. This application filed April 18,

' 1923. Serial No. 633,011.

' and more general fields of usefulness the invention is especially designed for use in shoe stitching machines of the lock-stitch type and is an improvement over the feed mechanism shown in my previous application for patent, Serial No. 551,544, filed April 11, 1922. This application is a substitute for application Ser. No. 413,818, filed September 30, 1920. A principal object of the inven-' tion is to provide an improved system ofcon nections to'the feeding mechanism requiring the use of only a single small cam and having provision for quick and convenient adjust ment to vary the length of the feeding strokes. A further feature is to construct this system of connections with a minimum of working parts that cannot get out of adjustment. A still further feature is the arrangement of these parts inamanner so as to reduce wear to a minimum and thereby- .looking in the direction of the arrow 3 in- Fig. 1.

10 indicates the frame of a sewing machine of the lock-stitch type bearing a work support 11 and just back of the work supporting face thereof is mounted an axis shaft 12 on which is journaled for oscillation the needle carrier 13 and awl carrier 14 and also the needle guide 15. Provision is here made for actuating the thread looper mechanism from the needle carrier, but as this forms no part of the present invention it need not be further described. The needle and awl carriers and the needle guide are actuated by a pitman bar 16 which extends diagonally downwith a handle at its outer .end.

ward and is engaged with a crank pin 17 carried at the outer end of a short crank 18 which is fixed to the main drive shaft D of the machine. A projecting roll of the crank pin 17 engages an elongated slot in the arm 19 which is fixed to a stub shaft 20 which serves as a pivot therefor. It will be seen that when the main drive shaft D is rotated the crank pin 17 will carry the slotted arm 19 around its pivot 20,, which being eccentric of the drive shaft D, will receive therefrom a slow and fast motion. The stub shaft 20 has fixed at its outer end a crank 21 hearing a pivot pin 22 which engages the lower end of a link bar 23 which in turn has its upper end scribed herein. 'The' rotation of the stub shaft 20 imparts an oscillatory movement to the shaft 25 through the link bar 23 and the lever :24. Journaled 0n the shaft 25 and a short distance inward of the framework 10 is a hub piece 26 hearing a half bevel gear 27 which meshes with a bevel pinion 28 which is vertically journaled between a laterally disposed web 29 extending from the frame work of the machine'and a bracket 30 fastened to said frame. Integral with the bevel pinion 28 is a small cam 31 adapted to be engaged by a fork 32 at the rear end of a lever 33,-the front end of which bearsa yoke 34 which engages-the hub 35 of the awl carrier. The lever 33 is slidably fulcrunied on a block 36 which is slidably held ina slot '37. of theweh 29 and is engaged by the forked end of a lever 38 which is pivoted at 39 in the frame work of the machine and extends from just beneath the web 29 outward being equipped By the manipulation of the lever 38 the fulcrum 36 may be moved forward or backward as desired to lengthen or shorten the distance of feed. The lever 38 may be held in adjusted position by'means of a pin 40 which may be pushed through a hole drilled therefor in the lever and extending upward into one of a series of holes 41 in the web 29 as it is brought into register therewith. In the operation of the machine, the shaft 25 is oscillated through one half a turn, and the half bevel 27 keyed thereto being twice the diameter of the pinion 28 rotates the cam 31 a complete revolution. This actuation occurs at a time when the awl has been pushed up through the work piece and the turning of the cam 31 shifts the lever 33 on its fulcrum thereby moving the a'wl a short distance. At the limit of movement the awl is instantly withdrawn and the cam 31 returns to its initial position for a new feed movement.

' The cam 31 is formed with a larger concentrio portion 31* and a smaller concentric portion 31 opposite thereto with inclined portions 31 extending between, and merging into the concentric portions 31, 31 Thus in the rotation of said cam the lever 33 has the forks thereof engaged to move the lever, and hence to shift the awl, positively in both directions under the action of the inclined cam portions 31, with a dwell at the end of each movement while the concentric cam por-" Patent is 1. Feed mechanism for sewing machines, comprising an awl mounted for sidewise movement, a lever engageable therewith for shifting said awl, means associated therewith for operating said lever consisting in a cam, and connections for oscillating the same from the main shaft of the machine, said connections constructed and arranged to impart oscillatory movement to said cam with a full rotation in each direction and at Varying rates in different parts of its movement.

2. Feed mechanism for sewing machines. comprising an awl mounted for sidewii e movement, a lever engageable therewith for shifting said awl, means associated therewith for operating said lever consisting in a cam having a pinion rigid therewith, a relat vely larger gear segment engaging said pinion, and a lever and link system for operating said gear segment from the main shaft arranged in proportion to oscillate said gear segment to an extent snfiicient to move the cam a full rotation in each direction.

3. Feed mechanism for sewing machines, comprising an aw] mounted for sidewise movement, a lever connected to operate the same, a cam engaging the lever, a main shaft, and connections for operating the cam from the main shaft to impart oscillatory movement to the cam with a full rotation in each direction and with a variable rate of movement. I

In testimony whereof, I have signed my name to this specification.

FRANK A. LARSON. 

